Ontario, Parry Sound, Besner mine - Thucholite

This little pseudocubic thing came to me labelled as thucholite (an amorphous, slightly U-bearing variety of pyrobitumen or "anthraxolite"). It is soft, with low density, black streak, and weak radioactivity, so I've no particular reason to doubt the label. Photo on the left is the exterior, photo on the right shows a broken side exhibiting a subconchoidal fracture. It was originally embedded in massive feldspar and left behind a cubic-looking cavity in the feldspar when it fell out. Other associated minerals are allanite and biotite.

My question is about the (admittedly rough) cubic-looking shape. Just random? Or a pseudomorph after something truly cubic, like uraninite or pyrite? Anyone familiar with the Parry Sound area pegmatites ever see anything similar?




Edited 1 time(s). Last edit at 03/09/2012 08:52PM by Alfredo Petrov.

Alfredo,

According to Sabina Misc report 39, the radioactive Hydrocarbon, Thucholite, occurs as black irregular masses, nodules and cubic crystals up to 25mm along an edge and as veinlets in Feldspar. Also cubic crystals of Uraninite and massive Uraninite can occur in the Thucholite.. So to answer your question?? Yes, I believe it's possible to have a cubic crystal of Thucholite from this old Feldspar mine.
Cool looking piece!! Now it makes me wonder if one can still access this site??

Andrew.



Edited 2 time(s). Last edit at 03/09/2012 08:22PM by Andrew Johns.

Very nice and indeed very interesting!

Thanks, Andrew and Peter. Calling anything a cubic "crystal" of thucholite was probably a mistake on Sabina's part, because thucholite is an amorphous organic and so can't have a crystal shape. That's why I wondered whether it could be a pseudomorph after uraninite or something else, even though I've never heard of hydrocarbons pseudomorphing anything before. Proving pseudomorphism is often difficult, unless relicts of the original mineral are present, which there may be, if uraninite is included in the thucholite.

Edit: Sabina probably copied the "thucholite crystals" error from the 1930 American Mineralogist article linked by Ronald below.



Edited 1 time(s). Last edit at 03/09/2012 10:04PM by Alfredo Petrov.

Hi Alfredo,

I can't answer your question directly from experience but here's some interesting papers that are relevant.
[www.minsocam.org] [www.terrapub.co.jp]

Ron

Thanks, Ronald! Very interesting papers. I had thought I might be a bit crazy to think that a hydrocarbon could pseudomorph uraninite, so I'm delighted to see that it is fairly certain this did indeed happen.

Thanks for the links Ron!! Very interesting to know that these are pseudomorphs!!

Thanks for the great links Ronald!

Alfredo,

I have a similar "crystal" that I bought from Gilbert Gauthier, years ago. He traded it from the Sorbonne and it is labelled thucholite, as well. I've known about the locality for years and how the pseudomorph was possible. I've not visited the spot.

FYI
David K. Joyce

Alfredo,
Here is another paper.
Laszlo